The present application relates generally to systems and methods for separating an object from tissue in a patient, and more specifically, to techniques for removing pacing leads from a patient.
Cardiac pacing systems typically include a pacemaker and a pacing lead, which are placed inside the body of a patient. The pacemaker includes a power source and circuitry configured to send timed electrical pulses to the pacing lead. The pacing lead carries the electrical pulse to the heart to initiate a heartbeat, and transmits information about the heart's electrical activity to the pacemaker. The pacing lead can include a fixation mechanism that holds the lead to the cardiac tissue. In some cases, a pacing lead is inserted through a vein and guided into a heart chamber where it is attached with the heart. In other instances, a pacing lead is attached to the outside of the heart. A common problem associated with pacing leads is the development of scar tissue or adhesions where the pacing lead contacts the patient's body tissue. Patient tissue can become attached with the pacing lead, and thus removal or extraction of the pacing lead may present complications.
Current pacing lead extraction techniques include mechanical traction, mechanical devices, and laser devices. Mechanical traction is often accomplished by inserting a locking stylet into the lead and pulling to remove it. In some cases, for example where mechanical traction is ineffective, dilating telescopic sheaths can be used to strip away the scar tissue adhering the lead to the body. Unfortunately, metal sheaths that are currently used to strip scar tissue from implanted leads often cannot traverse the tortuous lead path, and in many instances can only be used in proximal locations. Currently used plastic sheaths may be able to access certain distal lead locations, but often suffer from poor torque properties, low radiopacity, and ineffective penetration into hard tissue because they have soft tips that deform when in contact with the hard tissue. Dilation techniques often involve pushing tissue away from the lead when the sheath is pushed longitudinally along the lead. However, longitudinal forces can be easily lost during the procedure by tortuousity or curvature in the lead and by friction encountered within the anatomy or over the pacing lead. Longitudinal forces also may require heavy counter traction on the lead-that can result in pacing lead breakage. Some mechanical sheaths have proposed trigger mechanisms for extending a blade from a sheath. At least some of these devices, however, involve complicated activation mechanisms and may not be well suited for negotiating the tortuous paths present in certain vascular or physiological environments. Laser devices typically employ laser energy to cut the scar tissue away from the lead thus allowing for removal. Although effective in some circumstances for removing chronic implanted pacing leads, many laser systems can be expensive and unaffordable to many treatment centers.
What is needed are improved mechanical devices and methods for extracting pacing leads as well as other objects. These techniques can provide effective alternatives to currently used dilating lead extraction sheaths and laser systems.